A study on permeability of CH4 pre-adsorbed Yangquan coal matrix-plug to CO2 and He

Jianli Yang, Fangxin Tang, Jun Zhang, Zhenyu Liu, Yunmei Li, Hongxian Niu, Andreas Busch, Niels van Wageningen

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The CO2 permeability of a CH4 saturated coal matrix-plug (Ø 6 mm, length 13mm), from Yangquan, China, was studied by carrying out CO2 breakthrough tests at 40°C. The similar tests were performed with respect to the inert gas He for comparison. The breakthrough tests were carried out in a self-confining flow cell equipped with an online thermal conductivity detector for continuous monitoring the CO2 or He signal. The retention of gas by coal and the influence of the pore gas pressure were investigated. It was found that unlike He there was significant residual CO2 left in the coal matrix even after CO2 was flushed by CH4 for 36 hours. It reveals that coal has a relative stronger retention capacity for CO2, which leads to the difference in its breakthrough time for different CH4 flushing time. No notable residual He was found during the breakthrough tests. The He permeability of the test coal plug was found to be significantly higher than for CO2. The obtained permeability coefficients of the coal plug with respect to CO 2 or He at steady state are similar for the repeat breakthrough tests. This implies that no significant structural changes occurred during the tests. The permeability coefficients varied with pore gas pressure due to changes in pore wall interactions (Klinkenberg effect), the swelling of coal and the adsorption boundary layer.

Original languageEnglish
Title of host publication28th Annual International Pittsburgh Coal Conference 2011
Number of pages9
Publication statusPublished - 2011
Event28th Annual International Pittsburgh Coal Conference 2011 - Pittsburgh, PA, United States
Duration: 12 Sept 201115 Sept 2011


Conference28th Annual International Pittsburgh Coal Conference 2011
Abbreviated titlePCC 2011
Country/TerritoryUnited States
CityPittsburgh, PA


  • Breakthrough test
  • CH
  • CO
  • Coal
  • Permeability

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geotechnical Engineering and Engineering Geology


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